System and method for providing user input information to multiple independent concurrent applications

ABSTRACT

In a system for providing user input information to multiple independent, concurrent applications, the applications send subscription messages to a device receiving user input such as a telephone receiving key presses from a keypad. Each subscription message identifies a pattern of user input that the application is to be notified of. The device monitors the user input to identify the occurrence of the identified patterns. When a specified pattern of user input is detected, the device notifies the corresponding application via a signaling channel linking the application with the device. The subscription messages use regular expressions including various formats to specify the patterns of interest, such as a single digit (explicitly or wildcard), one of a set of digits, a range of digits, and a repeating pattern of digits. The subscription messages can also contain tags associated with the regular expressions, which are returned to the application upon reporting the occurrence of a pattern to enable the application to readily identify the context of the notification.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 10/785,501 (Now U.S. Pat. No. 7,406,696 B2), filedon Feb. 24, 2004, entitled SYSTEM AND METHOD FOR PROVIDING USER INPUTINFORMATION TO MULTIPLE INDEPENDENT, CONCURRENT APPLICATION.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

The present invention is related to the field of user input to computerapplications, and in particular to the use of a single input device suchas a telephone keypad to provide user input to multiple concurrentcomputer applications.

Many communications and information services are enabled by telephoneaccess to computer applications. A common mode for interacting with suchcomputer applications is through a touch-tone telephone. Services oftenconnect multiple applications to the user. For example, it is possiblefor a voice messaging service to be accessed through a pre-paid service.However, this creates a modality problem. For example, the pre-paidplatform might wish to know when the user presses and holds the “#” keyfor a relatively long time (this being referred to as both the “longpound” and the “long octothorpe”), while the voice messaging platformmight wish to know when the user enters digits, such as for menunavigation. The modality problem is that all digits entered by the usertoday get sent to both applications, as the digits are sent and bothapplications listen to the bearer channel. Each application must beprepared to receive and discard notifications of key presses in which ithas no interest, complicating the design of the application as well aswasting the use of processing and communications resources duringoperation.

Numerous applications have been deployed for use in conjunction with thetraditional time-division-multiplexed (TDM)-based telephone network. Inmany cases the applications simply receive the TDM-based “in-band” mediastream, i.e., the voice channel, and the applications are responsiblefor continually decoding the media and monitoring for the presence ofcertain user input of a signaling nature, such as tones indicating thata particular key on the telephone keypad has been pressed. Certainimprovements to the TDM network have been made, such as the AdvancedIntelligent Network (AIN), which have the goal of separating signalingtraffic from media traffic. However, in practice most of the applicationlogic resides in an “intelligent peripheral” that is coupled along themedia path, because of the low-level, device control nature of theassociated protocols. There are too many messages with too short alatency budget for a total separation of application logic from theIntelligent Peripheral. The result is that application developers writetheir applications for deployment on the intelligent peripheral, usuallywith proprietary intelligent peripheral languages. Thus, AIN does notfulfill the promise of separating application logic from mediaprocessing.

The situation is more complex for the packet-switched environments, suchas Voice-over-IP. Existing approaches such as H.248.1 (MEGACO), SessionInitiation Protocol (SIP) and an in-band technique described in RFC 2833are described in turn.

H.248.1 (MEGACO) has a provision for reporting key press digits detectedor generated by an “endpoint”, which in H.248.1 is a media gateway (MG).The MG can be an IP phone, an access gateway, or a trunking gateway. Inthe case of the IP phone, the IP phone can transmit the key pressesdirectly at the protocol level. In the case of a gateway, the gatewaycan detect the key presses using DTMF detectors. Media Gateway ControlProtocol (MGCP) is a proprietary Cisco protocol that operates in muchthe same manner as H.248.1. These protocols employ a master-slaveapproach in which a Media Gateway Controller (MGC) commands the MG(using a device control protocol signaling link) to connect a tonedetector to an incoming circuit and wait for a digit map match. When theMG detects a key press pattern of interest, it notifies the MGC over thesame signaling link, returning the actual digit string detected.

In H.248.1, however, one and only one MGC may control the resources inan MG. Applications that have an interest in user signaling must be apart of the MGC application—there is no provision for independent,third-party applications to receive user signaling information. In MGCP,a first MGC may “pass off” control to a second MGC, but one and only oneMGC may control a resource at any given time. The limitation of one andonly one controller controlling a resource is a direct result of themaster/slave nature of the MGCP and H.248.1 protocols. That is, theprotocol requires the MG to be in an exclusive relationship to an MGC.Although these protocols also allow for “virtual MGs” within a physicalMG, in which case there may be multiple MGCs serving as masters to theset of virtual MGs in a single physical MG, the virtual MGs are simplypartitions of a physical MG. There is no provision for enabling multipleindependent applications to selectively obtain user signalinginformation from a single stream of user input.

It has been proposed that a peer-to-peer protocol such as the SessionInitiation Protocol (SIP) be used to transport key press signaling, suchas via the SIP INFO method. The proposed mechanism closely follows theprotocol of MGCP and H.248.1, including the use of MGCP and H.248.1messages for specifying digit maps and notifications. However, theproposals have envisioned only a single application requestingnotifications, which is a result of there being no mechanism foraddressing endpoints of interest.

Cisco Systems has introduced a method for transporting DTMF digits usingSIP in the SIP signaling path using the SIP NOTIFY method. However, thismethod has a number of disadvantages. First, notifications can only goto a single egress gateway—it is not possible for a third-partyapplication to register for notifications. Second, the egress gatewayreceives notifications of every DTMF digit, whether it has an interestin them or not. Third, there is no provision for selectively passingthrough or clamping the DTMF tones from the media stream. If the ingressgateway passes DTMF, there is the risk of network elements interpretingboth the in-band DTMF and the corresponding DTMF signaling received viathe NOTIFY mechanism, potentially resulting in incorrect operation.

Another proposed method of transporting key press signaling is to usein-band representations for the keys. For example, RFC 2833 describestransporting key presses as named events, rather than as digitalwaveforms representing the key presses. While this approach uses lessbandwidth and processing resources in the media path, it has seriousdrawbacks that limit its usability. First, a point-to-point mediarelationship between the endpoint and the application is generallyassumed, leaving no provision for third-party involvement withcollecting digits. Although in theory RFC 2833 could be used withthird-party applications, rather complicated and unrealistic setup andoperation are required. Additionally, because of the particular way thatRFC 2833 handles redundancy, it does not meet the reliabilityrequirements for signaling traffic. Moreover, RFC 2833 uses morebandwidth than is necessary, by sending multiple copies of the samepacket for normal, lossless operation. Finally, applications receive allkey presses, whether they have an interest in the key presses or not,making for inefficient use of communication and processing resources.

Thus what is needed is an efficient system and method for detecting andnotifying applications of a single mode of user input, such as user keypresses, where the user input signaling follows a signaling pathdistinct from the media path, and that provides for multiple,independent applications to receive the signaling independently.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention, a system and method forproviding user input information to multiple independent, concurrentapplications is disclosed.

The applications generate respective subscription messages that areprovided to a device receiving input of a predetermined type from auser, such as key presses on a telephone keypad. The subscriptionmessage for each application identifies a respective pattern of the userinput that the application is to be notified of. The device may receivethe input directly, such as in the case of a telephone that receives keypress information directly from the telephone keypad. Alternatively, thedevice may be of a type, such as a media proxy, that resides along amedia path between the user and the application, in which case thedevice obtains the user input from the media stream.

The device monitors the input from the user to identify the occurrenceof the respective patterns identified in the subscription messages. Uponthe occurrence of the pattern in a given subscription message, thedevice notifies the corresponding application via a signaling channellinking the application with the device. In general, the device onlynotifies the particular application that provided the subscriptionmessage, and thus processing and communications resources are conserved.

The subscription messages use regular expressions that can includevarious types of formats to specify the patterns of interest. Forexample, the formats can specify a single digit (either explicitly or inwildcard form), one of a set of digits, a range of digits, and/or arepeating pattern of digits. The subscription messages can also containtags associated with the regular expressions. When a match is detectedand reported to the application by the device, the tag is also returned,enabling the application to easily determine exactly what response tothe input is appropriate without needing to maintain a large amount ofinternal state information.

Other aspects, features, and advantages of the present invention will beapparent from the Detailed Description that follows.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention will be more fully understood by reference to thefollowing Detailed Description of the invention in conjunction with theDrawing, of which:

FIG. 1 is a block diagram of a first system for signaling user key pressinformation to applications in accordance with the present invention;

FIG. 2 is a block diagram of a second system for signaling user keypress information to applications in accordance with the presentinvention;

FIG. 3 is a block diagram of a third system for signaling user key pressinformation to applications in accordance with the present invention;

FIG. 4 is a block diagram of a fourth system for signaling user keypress information to applications in accordance with the presentinvention;

FIG. 5 is a diagram of a key press buffer and associated pointers usedin any of the systems shown in FIG. 1-4; and

FIG. 6 is a diagram of a schema for a key press markup language (KPML)used in any of the systems shown in FIG. 1-4.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a first embodiment in which an application 10 (which is aSIP User Agent (UA)) directly interacts, on a given two-party dialog,with an “end point device” 12. The application 10 is connected to theend point device 12 by both a SIP connection 14 (for signaling) and oneor more Real-Time Protocol (RTP) connections 16 (for media). In thisscenario, the application 10 requests that the end point device 12report via the SIP connection 14 on key press events that might normallyemanate from the end point device's RTP port 18. The illustratedconfiguration can represent, for example, a toll by-pass scenario wherethe end point device 12 is an ingress gateway and the application 10 isan egress gateway.

In the case shown in FIG. 1, the application 10 requests digitnotification on the same dialog established for the call, between SIPports 20 and 22. The use of SIP and RTP in FIG. 1 is for exemplarypurposes only. Other signaling mechanisms such as H.323 can be used, andother bearer mechanisms such as ATM or TDM can be used.

In general, the end point device 12 may receive the input directly, suchas in the case of a telephone that receives key press informationdirectly from the telephone keypad. Alternatively, the device may be ofa type, such as a media proxy, that resides along a media path betweenthe user and the application, in which case the end point device 12obtains the user input from the media stream. An example of such aconfiguration is shown below. In general, the end point device 12includes hardware and software processing resources and interfaces inaccordance with its function in the system. In particular, the end pointdevice 12 includes hardware for monitoring the user input to detectpatterns of interest, as described in more detail below, and one or moreprocessors programmed to implement the signaling functionality describedherein.

FIG. 2 shows a second embodiment that supports a third-party application24 that is interested in user key presses occurring in the context of anestablished two-party SIP dialog between the end point device 12 and thefirst application 10. The third party application 24 addresses theparticular media stream by referencing an established SIP dialogidentifier that refers to the dialog between the SIP ports 20 and 22.

FIG. 3 shows a third embodiment employing a “media proxy” 26 thatmonitors the media stream among a plurality of endpoints. A media proxyis a device that forwards media streams under the control of a signalingcomponent that provides, at a minimum, instruction as to the source anddestination addresses. In addition to the media forwarding function, themedia proxy 26 can also do light media processing, such as tonedetection. An example of a media proxy is the A1-G2 MF from SnowShoreNetworks, Inc.

In FIG. 3, the media proxy 26 has established connections to a firstendpoint User Agent UAa 28 and a second endpoint User Agent UAb 30. Arequesting application 32 uses dialog identifiers to identify the streamto monitor. The default is to monitor the media entering the end pointdevice. For example, if the requesting application 32 uses the dialogrepresented by SIP ports 34 and 36, then the media coming from UAa RTPport 38 is monitored. Likewise, specifying the dialog represented byports 40 and 42 directs the media proxy 26 to monitor the media comingfrom UAb RTP Port 44. The requesting application 32 can monitor thereverse direction or other, related streams. There could also bemultiple streams if there are multiple audio sources, for example.

As shown in FIG. 4, a plurality of applications may be interested inreceiving different notifications of digit map patterns. Applications 46and 48 make requests directly to, and receive reports directly from, anend point device 50. Other applications 52-1, 52-2, . . . 52-n registerwith a controlling, or “aggregation”, server 54, which collapses thevarious requests into as few as one KPML request to the end point device50.

One problem with employing an aggregation server 54 is its potential tobecome a bottleneck, because it must process all of the requests andforward them on to the end point device 50. Another problem is that somepatterns may have complex inter-key-press timing relationships within apattern, but not across independent pattern requests, thus making itdifficult to specify values for the various timers. Finally, theaggregation server 54 must disambiguate and forward responsesappropriately in the face of conflicting or overlapping expressions fromthe different requesting applications 52. Thus, to avoid such problems,it is generally preferred that the individual requesting applications,such as applications 46 and 48 in FIG. 4, make requests directly to anend point device such as end point device 50. Note that this approachstill supports the aggregation model presented by the aggregation server54.

In addition to reducing network traffic, one of the goals of thepresently disclosed technique is to reduce processing requirements atthe requesting applications. For example, assume the first requestingapplication 46 of FIG. 4 is looking for “***”, while the secondrequesting application 48 is looking for “L#”, the octothorpe keypressed for a time. When the end point device 50 detects the “***”pattern, it would be inefficient to send a report to the secondrequesting application 48. Thus, the end point device 50 sends thenotification only to the first requesting application 46.

The system described herein uses a subscription protocol mechanism,whereby a party such as the application server 32 subscribes to the keypress state of a device such as the media proxy 26 or end point device12. The SIP SUBSCRIBE/NOTIFY mechanism, as described in RFC 3265, can beemployed. If media sessions are set up using the SIP INVITE mechanism,as described in RFC 3261, then requesting applications can use the SIPcall identifiers to identify the media leg to be monitored. Inalternative embodiments, session description protocol (SDP) identifierssuch as Internet Protocol address and Port numbers can be used.

The SIP SUBSCRIBE/NOTIFY mechanism provides a means for handlingmultiple, independent requests. Namely, subscriptions on different SIPdialogs are independent. In addition, a subscription on a particulardialog, with a unique event identifier tag (the “id” tag to the “event”entity in the SUBSCRIBE request) is also an independent subscription forthe purposes of key press handling and reporting.

SUBSCRIBE/NOTIFY protocols provide subscription state management.Following the mechanics of RFC 3261, if an end point device 12 receivesa SUBSCRIBE request on an existing subscription, the end point device 12unloads the current subscription and replaces it with the new one.

One goal of the presently disclosed system is to reduce network trafficby consolidating multiple digit presses into one notification message.The system can take advantage of the fact that many telephonyapplications are interested in not only a single key press, but multiplekey presses. For example, collecting a North American Numbering Plantelephone number requires collecting 10 digits, while collecting aPersonal Identification Number (PIN) code may require collecting 4 to 6digits. The system achieves this goal by having the requestingapplication include regular expressions describing the patterns tocollect. The following section describes one embodiment of a regularexpression syntax that can be employed. This syntax is referred to asDRegex, for digit regular expression. It should be noted that “whitespace” is removed before DRegex is parsed, which enables sensibleprinting in XML without affecting the meaning of the DRegex string.

Table 1 describes the use of DRegex. Table 2 gives some examples ofDRegex regular expression formats.

TABLE 1 DRegex Formats Format Matches digit single digit 0-9 and A-D # #key * * key [digit selector] Any digit in selector [{circumflex over( )}digit selector] Any digit NOT in selector [digit-range] Any digit inrange x Any digit 0-9 . Zero or more repetitions of previous pattern |Alternation {m} m repetitions of previous pattern {m,} m or morerepetitions of previous pattern {, n} At most n (including zero)repetitions of previous pattern {m, n} at least m and at most nrepetitions of previous pattern Lc Match the character c if it is“long”; c is a digit, #, or *.

TABLE 2 DRegex Examples Example Description 1 Matches the digit 1 [179]Matches 1, 7, or 9 [{circumflex over ( )}01] Matches 2, 3, 4, 5, 6, 7,8, 9 [2-9] Matches 2, 3, 4, 5, 6, 7, 8, 9 x Matches 0, 1, 2, 3, 4, 5, 6,7, 8, 9 2|3 Matches 2 or 3; same as [23] 00|011 Matches the string 00 or011 0. Zero or more occurrences of 0 [2-9]. Zero or more occurrences of2-9 *6[179#] Matches *61, *67, *69, or *6# 011x{7, 15} 011 followed byseven to fifteen digits L* Long star

Referring again to FIG. 4, a first requesting application 46 requeststhat an end point device 50 report detected key presses. The requestingapplication 46 registers for a pattern, such as “***” (three stars insuccession), using the SUBSCRIBE mechanism. When the end point device 50detects the pattern, it sends a NOTIFY message to the requestingapplication 46, noting the detection of the pattern. Example 1 shows arequest, using an embodiment of a protocol language referred to as theKeypress Markup Language (KPML).

<?xml version=“1.0” encoding=“UTF-8”?> <kpmlxmlns=“urn:ietf:params:xml:ns:kpml”xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance”xsi:schemaLocation=“urn:ietf:params:xml:ns:kpml kpml.xsd” version=“1.0”><request> <pattern> <regex>***</regex> </pattern> </request> </kpml>

Example 1 Single Regular Expression Request

The message in Example 1 is a request registering a set of patterns, ofwhich there is only a single regular expression, that of the three stars(“***”).

A requesting application can also register for multiple patterns. Forexample, the requesting application could look for any of a set ofpatterns “***”, “*1”, “*61”, and “*62”, as shown in Example 2.

<?xml version=“1.0” encoding=“UTF-8”?> <kpmlxmlns=“urn:ietf:params:xml:ns:kpml”xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance”xsi:schemaLocation=“urn:ietf:params:xml:ns:kpml kpml.xsd” version=“1.0”><request> <pattern> <regex>***</regex> <regex>*1</regex><regex>*61</regex> <regex>*62</regex> </pattern> </request> </kpml>

Example 2 Multiple Regular Expressions Request

There are different techniques that can be used to determine whatpattern matches a given key press string, including for example longestmatch, shortest match, or most specific match. The matching algorithm touse can be specified in the KPML message. Although in many cases thelongest match will be preferable, this technique has the problem thatthe system will always wait for the next digit, even if the best matchhas occurred. That is, all key press collection events end with atimeout.

To improve the user experience by having fast reporting of a match,while maintaining the longest match property, the system uses a set ofspecial timers and the specification of an Enter Key Sequence. Thetimers are the critical timer, the inter-digit timer, and the extradigit timer. The critical timer is the time to wait for another digit ifthe collected digits can match a pattern. The extra timer is the time towait after the longest match has occurred (presumably for the returnkey). The inter-digit timer is the time to wait between digits in allother cases. Note there is no start timer, as that concept does notapply in the KPML context.

The Enter Key Sequence is a method whereby one specifies a key press orstring of key presses that indicates to the system that entry iscomplete. The system reports immediately with a match or no match errorupon receipt of the Enter Key Sequence. For convenience, the system doesnot send the Enter Key Sequence in the report. This saves the requestingapplication from having to trim irrelevant information. Note that theEnter Key Sequence cannot also be a substring in the regular expression.

For patterns such as the long octothorpe, applications instruct thedevice what constitutes “long” by setting a “longtimer” attribute in the<pattern> tag to the number of milliseconds desired. Some phones,particularly private branch exchange (PBX) phones, transmit a digit fora preset length of time, such as 50 ms, irrespective of how long theuser presses the respective key. To enable applications to respond tosaid devices, applications may indicate to the device to consider arepetition of a key press within the longtime time period. Applicationsindicate this behavior to the device by setting the longrepeat attributeto “true” in the <pattern> tag.

Example 3 shows an example of a request that registers for a longoctothorpe. With a longtimer value of 2000, the device will look for aminimum key press duration of two seconds (2000 milliseconds). Thisexample also directs the device to match a succession of octothorpe keysfor two seconds as long key press duration by setting longrepeat totrue.

<?xml version=“1.0” encoding=“UTF-8”?> <kpmlxmlns=“urn:ietf:params:xml:ns:kpml” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xsi:schemaLocation=“urn:ietf:params:xml:ns:kpml kpml.xsd” version=“1.0”> <request> <pattern longtimer=“2000” longrepeat=“true”><regex>L#</regex> </pattern> </request> </kpml>

Example 3 Long Octothorpe Request

Some applications care to continuously monitor the stream for aparticular pattern, while other applications look for only a singleoccurrence of a particular pattern, at which time the application isfinished monitoring the end point device or may register a different setof patterns. The first type of request is referred to as a “persistent”request, while the second type is termed a “one-shot” request. Thesystem provides for the requesting application to specify the nature(persistent or one-shot) of the request.

It is advantageous to refrain from notifying applications of key pressesthat are not of interest. However, it is possible that a human user maypress spurious keys or accidentally press an incorrect key. Applicationsneed to perform error recovery in this situation. The disclosed systemaddresses this problem by starting an inter-digit timer upon detectionof the first key that matches the first character of any regularexpression in a subscription. This inter-digit timer restarts afterevery key press detected. If the inter-digit timer expires, the endpoint device sends a failure notification to the requestingapplication(s) for which the key presses started to match patterns. Thisnotification enables the requesting application to take differentactions based on the incomplete key presses.

Another situation that can occur is for the end point device to startcollecting key press events and the media dialog to terminate before apattern matches. Again, the end point device sends the key pressescollected up to the point of the dialog termination to the requestingapplication.

The system and protocol described herein could use any of a variety ofmessage transport mechanisms. As described herein, one preferredtransport employs SIP SUBSCRIBE and NOTIFY requests to transport an XMLmarkup called KPML. Those skilled in the art could derive alternaterepresentations for the protocol messages described herein, such asASN.1 notation for example.

As shown in Example 3, a KPML message contains a <request> entity thatincludes a <pattern> tag with a series of <regex> elements. The <regex>element specifies a digit pattern for the device to report on. Because arequesting application may need to know which <regex> of a plurality of<regex>s matched, KPML supports a tag attribute to the <regex> element.When there is a match, the report from the end point device includes thetag of the match's<regex> element. Example 4 shows the case where aseven-digit number matches the “local” tag, a 1+ten-digit number matchesthe “ld” (or long distance) tag, and a 011 followed by a number and fiveto fifteen digits matches the “iddd” (or international direct distancedialing) tag. A sample response is in Example 5.

<?xml version=“1.0” encoding=“UTF-8”?> <kpmlxmlns=“urn:ietf:params:xml:ns:kpml” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xsi:schemaLocation=“urn:ietf:params:xml:ns:kpml kpml.xsd” version=“1.0”> <request> <pattern extradigittimer=“1000”interdigittimer=“5000”> <regex tag=“local”>x{7}</regex> <regextag=“ld”>1x{10}</regex> <regex tag=“iddd”>011x{5,15}</regex> </pattern></request> </kpml>

Example 4 Use of a Tag to Identify which Pattern Matched

<?xml version=“1.0” encoding=“UTF-8”?> <kpmlxmlns=“urn:ietf:params:xml:ns:kpml” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xsi:schemaLocation=“urn:ietf:params:xml:ns:kpml kpml.xsd” version=“1.0”> <response code=“200” text=“OK” digits=“17035551212”tag=“ld”/> </kpml>

Example 5 Tagged Response

A requesting application may advantageously use the tag attribute toencode, for example, state information. In this way, the requestingapplication can be a stateless, stimulus driven application. By usingthe tag attribute to carry state, the requesting application need notcarry per-session state. This results in a significant savings in memoryand processing requirements at the requesting application, thus offeringhigher scale and performance for the application.

For example, Example 6 shows the request for a first device, whileExample 7 shows the request for a second device. The server can tell thedifferent requests apart from the unique prefix, in this case “id00” and“id01” for Example 6 and Example 7, respectively. Note that the tags areopaque strings and can contain however much state information the clientrequires. In the examples here, the identifiers “id00” and “id01” areenough to associate the results with a session. The identifiers can haveany arbitrary state information that is meaningful to the application.For example, a tag might be “from-host-192.168.1.12 at step 24cookie=‘23d0ij32d0ioicq3icoiqwjemf’”, representing host information,sequence information, and arbitrary data.

<?xml version=“1.0” encoding=“UTF-8”?> <kpmlxmlns=“urn:ietf:params:xml:ns:kpml” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xsi:schemaLocation=“urn:ietf:params:xml:ns:kpml kpml.xsd” version=“1.0”> <request> <pattern extradigittimer=“1000”interdigittimer=“5000”> <regex tag=“id00-local”>x{7}</regex> <regextag=“id00-ld”>1x{10}</regex> <regex tag=“id00-iddd”>011x{5,15}</regex></pattern> </request> </kpml>

Example 6 Use of a Tag to Identify Server State (Part 1)

<?xml version=“1.0” encoding=“UTF-8”?> <kpmlxmlns=“urn:ietf:params:xml:ns:kpml” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xsi:schemaLocation=“urn:ietf:params:xml:ns:kpml kpml.xsd” version=“1.0”> <request> <pattern extradigittimer=“1000”interdigittimer=“5000”> <regex tag=“id01-local”>x{7}</regex> <regextag=“id01-ld”>1x{10}</regex> <regex tag=“id01-iddd”>011x{5,15}</regex></pattern> </request> </kpml>

Example 7 Use of a Tag to Identify Server State (Part 2)

Some devices buffer entered digits, and applications behave differentlywith respect to such buffered digits. Some applications may require thata user enter key presses only as the application is ready to receivethem, in which case any key presses entered prematurely should beignored or discarded. Other applications enable a user to “barge”through prompts or other delays in the user interface by entering keypresses in advance of their prompts, for example, and then acting on thebuffered key presses rather than discarding them.

In the disclosed system, the default is that the matching specified bynew requests is carried out with respect to buffered digits first, suchoperation enabling “barging” behavior by the user. However, the protocolprovides a <flush> tag in the <pattern> element to specify whether thebuffer should be flushed before any matching operations begin, which hasthe effect of ignoring any digits entered before receipt of the KPMLrequest. Additional detail on the digit buffering mechanism is providedbelow in conjunction with a description of key press “quarantining.”

As mentioned above, an end point device may support an inter-digittimeout value, which is the amount of time the end point device waitsfor user input before returning a timeout error result on a partiallymatched pattern. The application can specify the inter-digit timeout asan integer number of milliseconds by using an inter-digit timerattribute to the <pattern> tag. The default is 4000 milliseconds. If theend point device does not support the specification of an inter-digittimeout, the end point device silently ignores the request. If the endpoint device supports the specification of an inter-digit timeout, butnot to the granularity specified by the value presented, the end pointdevice rounds up the requested value to the closest value it cansupport.

KPML messages are independent, a property that enables multiplerequesting applications to simultaneously monitor a stream withoutinteracting with each other. One result of this independence, however,is that it is not possible for a requesting application to know whethera following request from another application will enable barging or wantthe digits flushed. Therefore, the end point device quarantines alldigits detected between the time of a notification and theinterpretation of the next request, if any. If the next requestindicates a buffer flush, then the end point device flushes allcollected digits from consideration from KPML requests received on thatdialog with the given event id. If the next request does not indicatethat buffered digits should be flushed, then the end point deviceapplies the buffered digits (if possible) against the digit mapspresented by the request's <regex> tags. If there is a match, the endpoint device issues the appropriate notification. If there is no match,the end point device flushes all of the collected digits on thatrequest's buffer.

By default, the end point device transmits in-band tones (RFC 2833events or actual tones) on the media channel in parallel with digitreporting via the signaling channel. Note that in the absence of thisbehavior, a user device could easily break called applications. Forexample, consider a personal assistant application that uses “*9” forattention. If the user presses the “*” key, the device holds the digitlooking for the “9”. However, the user may enter another “*” key,possibly because they accessed an IVR system that looks for “*”. In thiscase, the “*” would get held by the device, because it is looking forthe “*9” pattern. The user would probably press the “*” key again,hoping that the called IVR system just did not hear the key press. Atthat point, the user device would send both “*” entries, as “**” doesnot match “*9”. However, that would not have the effect the userintended when they pressed “*”.

On the other hand, there are situations where passing through tonesin-band is not desirable. Such situations include call centers that usein-band tone spills to effect a transfer. For those situations, a digitsuppression tag “pre” can be used in conjunction with the <regex> tag toindicate that the transmission of digits in the media stream should besuppressed. There can only be one <pre> in any given <regex>. An exampleof a request including a suppression tag is shown in Example 8.

If there is only a single <pattern> and a single <regex>, suppressionprocessing is straightforward. The end point device passes digits untilthe stream matches the regular expression <pre>. At that point, the endpoint device will continue collecting digits, but will suppress thegeneration or pass-through of any in-band digits. When reporting on amatch, the end point device will indicate whether it suppressed anydigits by including an attribute “suppressed” with a value of “true” inthe digit report.

<?xml version=“1.0” encoding=“UTF-8”?> <kpmlxmlns=“urn:ietf:params:xml:ns:kpml” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xsi:schemaLocation=“urn:ietf:params:xml:ns:kpml kpml.xsd” version=“1.0”> <request> <pattern> <enterkey>#</enterkey><regex><pre>*8</pre>x{7}|x{10}</regex> <regex>*6</regex> </pattern></request> </kpml>

Example 8 Digit Suppression

In Example 8, the end point device will begin to suppress digits afterreceiving the string ‘*8’. It then looks for seven or ten digits. If itreceives something other than a digit, receives the enter key sequence,or times out, then the end point device will return an error report.Note the second pattern, <regex>*6</regex> does not start the digitsuppression method.

Digit suppression can be optional for a device. If a device is notcapable of digit suppression, it should ignore the digit suppressionattribute and never send a suppressed indication in the digit report. Inthis case, it will match concatenated patterns of pre+value.

At some point during digit suppression, the end point device willcollect enough digits to the point it hits a <pre> pattern. Theinter-digit timer attribute indicates how long to wait once the userenters digits before reporting a time-out error. If the inter-digittimer expires, the endpoint issues a time-out report and transmits thesuppressed digits on the media stream.

Once the end point device detects a match and it sends a NOTIFY requestto report the digit string, the end point device stops digitsuppression. Clearly, if subsequent digits match another <pre>expression, then the end device starts digit suppression again.

After digit suppression begins, it might become clear that a match willnot occur. For example, take the expression “<regex><pre>*8</pre>xxx[2-9]xxxxxx</regex>”. At the point the endpoint receives“*8”, it will stop sending digits. Let us say that the next three digitsfrom the user are “408”, which match the “xxx” part of the pattern. Ifthe next digit is a zero or one, the pattern will not match, meaningthat there is no mechanism for re-enabling the sending of digits on themedia connection.

Applications should be very careful to indicate suppression only whenthey are fairly sure the user will enter a digit string that will matchthe regular expression. In addition, applications should deal withsituations such as no-match or time-out. This is because the endpointwill hold digits, which will have obvious user interface issues in thecase of a failure. Also, it is very important for the endpoint to have asensible inter-digit timer. This is because an errant dot (“.”) maysuppress digit sending forever. Reasonable values are on the order offour seconds.

One unique aspect of the presently disclosed system is the handling ofquarantined key presses. A quarantined key press is an event that doesnot yet match a regular expression. The system often quarantines keypresses between the time of a notification and, particularly in the caseof one-shot subscriptions, the receipt of a new subscription.

If the user presses a key not matched by the <regex> tags, the end pointdevice discards the key press from consideration against the current orfuture KPML messages. However, once there is a match, the end pointdevice quarantines any key presses the user entered subsequent to thematch. This behavior allows for applications to only receive digits thatinterest them.

Before the receipt of the first subscription, the end point device doesnot normally quarantine key press events. This can create a racecondition. Namely, the end point device can establish a session and havekey press events occur before the end point device receives the firstsubscription. If this is of concern, the end point device can beprovisioned to quarantine all key press events, or the end point devicecan be signaled at session establishment time that there will be asubscription. In the SIP environment, the first KPML subscription can beincluded as a separate MIME body part to the initial INVITE message.

At some point in time, the end point device has an indication toquarantine digits, either because of provisioning, explicit signaling,or receiving a subscription. That subscription will be associated with aSIP dialog or dialog/id pair. In the case of explicit provisioning orexplicit signaling, there will be an implicit subscription on the INVITEdialog. In the case of a SUBSCRIBE request, the subscription isassociated with the given SUBSCRIBE-initiated dialog. Again, the endpoint device considers a SUBSCRIBE request with a unique “id” tag to bea new subscription for quarantine purposes.

The importance of separate subscriptions comes from the per-subscriptionquarantine of key presses. This enables application consistency. Theapplication will get all key presses, in temporal order, which it isinterested in, without interference from the subscriptions of otherapplications.

It could be required that the current request determine the quarantinepolicy for post-notification processing. This makes sense when allsubscriptions come from a single application, which presumably is awareof its own quarantine needs. However, such an approach is not acceptablefor a system that must support multiple independent applications, eachpotentially unaware of the others. Each request must set its ownquarantine policy for the key presses already buffered.

Requests can explicitly flush the per-subscription key press buffer whenthe end point device loads a new KPML request on the given subscriptionby specifying the <flush>yes</flush> entity in the <pattern> tag. Also,requests can explicitly flush digits in the current subscription'sbuffer that have already been matched or considered by othersubscriptions by specifying the <flush>others</flush> entity in the<pattern> tag.

FIG. 5 shows a single key press buffer 56 for recording all key presses,with per-stream indices or pointers 58, 60 and 62 into the key pressbuffer indicating where in the buffer the stream is. Examples are givento illustrate operation of this buffer 56.

Consider the pattern <regex>xxxxxxxx</regex> specified by subscription1. In this case, the buffered digits 12345678 match the pattern. Thus,the pattern succeeds, the end point device reports the match, and thepointer 58 is subsequently positioned at buffer location 64.

Next, consider the pattern <regex>x{10}</regex>. In this case, thecollected digits 123456789# will never match the pattern, because “#” isnot a digit and will not match ‘x’. The pattern fails, the end pointdevice reports the failure, and the pointer 58 is subsequentlypositioned at buffer location 66.

Finally, consider the pattern <regex>***</regex>. In this case, the endpoint device scans the buffer until the first * at position 66, which isthe first character that matches the pattern, and thus bypasses thefirst 10 key presses entered. The pattern then succeeds, the end pointdevice reports the match, and the pointer 58 will be positioned atbuffer location 68.

Now consider what happens if a request specifies <flush>others</flush>and a <regex>x{7}</regex>. In this case, other streams have seen keypresses up to position 68, the position of buffer pointer 62. Thus theend point device moves the buffer pointer 58 to position 68 and thenstarts matching key presses. In this example, the pattern fails, asthere are only three digits before a non-digit key (the long #). Becausethe end point device has considered all key presses between thepositions pointed to by pointers 58 and 60, the end point device freesthe memory in the buffer between those positions.

The key press buffer can be made quite large, for example by employing alarge secondary storage device in the form of a hard disk. The end pointdevice can put parts of the key press buffer onto the secondary storagedevice, keeping more recently referenced buffered key presses in mainmemory. This operation is accomplished in a straightforward manner usingconventional virtual memory techniques.

Even with a large secondary storage device, it is possible to fill thebuffer completely, especially if a large number of media streams arebeing monitored and if many streams have multiple subscriptions. Toaddress this problem, the end point device can use a circular buffer.When the end-of-buffer pointer will overlap a given subscription'spointer, the subscription's pointer is set to the next subscriptionpointer, in increasing time order. The end point device also sets a“forced_flush” indicator for the subscription pointer, which is includedin the end point device's report on a match or failure and thensubsequently cleared.

Note that using a circular buffer is superior to having key presses ageout of the buffer. This is because there is no reason to remove keypress history if the memory is available. Likewise, under load, thebuffer may still overflow if requests do not free digits off of thebuffer fast enough. Nonetheless, the presently disclosed technique maybe used with non-circular buffers as well.

When the user enters key press(es) that match a <regex> tag, the endpoint device will issue a report. After reporting, the end point deviceterminates the KPML session unless the subscription has a persistenceindicator. If the subscription does not have a persistence indicator,the end point device sets the state of the subscription to “terminated”in the NOTIFY report. If the requestor desires to collect more digits,it must issue a new request. If the subscription has a persistenceindicator, then the device uses the same <pattern> to match againstfuture key presses.

KPML reports have two mandatory attributes, code and text. Theseattributes describe the state of a KPML interpreter on the end device.In the preferred embodiment, the SIP state of the subscription, such as“active” or “terminated”, is also a protocol parameter. If one were touse a transport other than SIP that does not convey the subscriptionstate, the subscription state must be one of the attributes of the KPMLreport.

Note that the KPML code is not necessarily related to the SIP resultcode. An important example is when a legal SIP subscription request getsa normal SIP 200 OK followed by a NOTIFY, but there is something wrongwith the KPML request. In this case, the NOTIFY would include the KPMLfailure code in the KPML report. Note that from a SIP perspective, theSUBSCRIBE and NOTIFY were successful. Also, if the KPML failure is notrecoverable, the end device will most likely set the Subscription-Stateto terminated. This lets the SIP machinery know the subscription is nolonger active.

If a pattern matches, the end point device emits a KPML report. Sincethis is a success report, the code is “200” and the text is “OK”. TheKPML report includes the actual digits matched in the digit attribute.The digit string uses the conventional characters ‘*’ and ‘#’ for starand octothorpe, respectively. The KPML report also includes the tagattribute if the regex that matched the digits had a tag attribute. Ifthe subscription requested digit suppression and the end devicesuppressed digits, the suppressed attribute indicates “true”. Thedefault value of suppressed is “false”. Embodiments of the device mayhave a datum indicating if the device terminated digit collection due tothe receipt of the Enter Key sequence in the KPML report. It may bedesirable to omit this datum, as many applications do not need thisinformation.

Example 9 shows a typical KPML response. This is an example of aresponse to the request shown in Example 4.

<?xml version=“1.0” encoding=“UTF-8”?> <kpmlxmlns=“urn:ietf:params:xml:ns:kpml” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xsi:schemaLocation=“urn:ietf:params:xml:ns:kpml kpml.xsd” version=“1.0”> <response code=“200” text=“OK” tag=“ld”digits=“17035551212”/> </kpml>

Example 9 Sample Response

There are a few circumstances in which the end point device will emit ano match report. They are an immediate NOTIFY in response to SUBSCRIBErequest (no digits detected yet), a request for service not supported bythe end device, or a failure of a digit map to match a string (timeout).Preferably, the NOTIFY in response to a SUBSCRIBE request has no KPML ifthere are no matching quarantined digits.

Example 10 shows a typical time-out response. Note the device reportsthe digits collected up to the timeout in the digits attribute of theresponse tag.

<?xml version=“1.0” encoding=“UTF-8”?> <kpmlxmlns=“urn:ietf:params:xml:ns:kpml” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xsi:schemaLocation=“urn:ietf:params:xml:ns:kpml kpml.xsd” version=“1.0”> <response code=“423” text=“Timer Expired”digits=“1703555”/> </kpml>

Example 10 Sample Time-Out Response

If there are quarantined digits in the SUBSCRIBE request that match apattern, then the NOTIFY message in response to the SUBSCRIBE requestincludes the appropriate KPML document.

Key presses collected using the disclosed method can contain sensitiveinformation, such as PIN codes, credit card numbers, or other personalinformation. Thus notifications should be secure, integrity checked, andnot accessible to unauthorized parties. Likewise, the end point deviceneeds to authenticate subscriptions and make sure the subscriber isauthorized to access the key press information. Moreover, subscriptionsalso need cryptographic integrity guarantees and need protection againstspoofing and man-in-the-middle attacks.

A technology known as Transport Layer Security (TLS) can be used fortransport security, and a separate technology known as S/MIME can beused for the SUBSCRIBE and NOTIFY methods to guarantee authentication,integrity, and non-repudiation.

Example 10 is an example of a schema that embodies the facets of thepreferred embodiment as described herein. A graphical representation ofthis schema is in FIG. 6.

<?xml version=“1.0” encoding=“UTF-8”?> <xs:schematargetNamespace=“urn:ietf:params:xml:ns:kpml” xmlns=“urn:ietf:params:xml:ns:kpml” xmlns:xs=“http://www.w3.org/2001/XMLSchema” elementFormDefault=“qualified”  attributeFormDefault=“unqualified”><xs:element name=“kpml”> <xs:annotation> <xs:documentation>IETF KeypadMarkup Language</xs:documentation> </xs:annotation> <xs:complexType><xs:choice> <xs:element name=“request”> <xs:complexType> <xs:sequence><xs:element name=“stream” type=“xs:string” minOccurs=“0”/> <xs:elementname=“pattern”> <xs:complexType> <xs:sequence> <xs:element name=“flush”minOccurs=“0”> <xs:complexType> <xs:simpleContent> <xs:extensionbase=“xs:string”/> </xs:simpleContent> </xs:complexType> </xs:element><xs:element name=“enterkey” minOccurs=“0”> <xs:complexType><xs:simpleContent> <xs:extension base=“xs:string”/> </xs:simpleContent></xs:complexType> </xs:element> <xs:element name=“regex”maxOccurs=“unbounded”> <xs:complexType mixed=“true”> <xs:sequence><xs:element name=“pre” minOccurs=“0”> <xs:complexType><xs:simpleContent> <xs:extension base=“xs:string”/> </xs:simpleContent></xs:complexType> </xs:element> </xs:sequence> <xs:attribute name=“tag”type=“xs:string” use=“optional”/> </xs:complexType> </xs:element></xs:sequence> <xs:attribute name=“persistent” type=“xs:boolean”use=“optional”/> <xs:attribute name=“interdigittimer” type=“xs:integer”use=“optional”/> <xs:attribute name=“criticaldigittimer”type=“xs:integer” use=“optional”/> <xs:attribute name=“extradigittimer”type=“xs:integer” use=“optional”/> <xs:attribute name=“longtimer”type=“xs:integer” use=“optional”/> <xs:attribute name=“longrepeat”type=“xs:boolean” use=“optional”/> </xs:complexType> </xs:element></xs:sequence> </xs:complexType> </xs:element> <xs:elementname=“response”> <xs:complexType> <xs:attribute name=“code”type=“xs:string”  use=“required”/> <xs:attribute name=“text”type=“xs:string”  use=“required”/> <xs:attribute name=“suppressed”type=“xs:boolean” use=“optional”/> <xs:attribute name=“forced_flush”type=“xs:boolean” use=“optional”/> <xs:attribute name=“digits”type=“xs:string” use=“optional”/> <xs:attribute name=“tag”type=“xs:string” use=“optional”/> </xs:complexType> </xs:element></xs:choice> <xs:attribute name=“version” type=“xs:string”use=“required”/> </xs:complexType> </xs:element> </xs:schema>

Example 10 Representative KPML Schema

Although in the foregoing description, the particular form of user inputconstitutes key presses from a telephone keypad, it will be appreciatedthat the disclosed system and method are also usable with other forms ofuser input and other devices. For example, the user input may constitutecertain patterns of speech that can be recognized by speech recognitionhardware/software and then made the subject of subscriptions andnotifications as described above. The disclosed system and method mayalso be used with devices such as personal computers (PCs), personaldigital assistants (PDAs), or other devices capable of accepting userinput in the form of touches or strokes on a screen using a finger or astylus. Additionally, the “user” generating the input need not be ahuman user, as in the case of a computer or other device generating keypress tones or other user input in a manner mimicking the behavior of ahuman user.

It will also be apparent to those skilled in the art that othermodifications to and variations of the disclosed methods and apparatusare possible without departing from the inventive concepts disclosedherein, and therefore the invention should not be viewed as limitedexcept to the full scope and spirit of the appended claims.

1. A method of providing user input information to a plurality ofindependent, concurrent applications, comprising: for each of saidplurality of applications, generating a respective subscription messageand providing the subscription message via a session based protocol to adevice receiving input of a predetermined type from a user, thesubscription message for each application identifying user inputcontent, the user input content including a respective pattern of userinput upon whose occurrence the application is to be notified; and atthe device, (1) monitoring the user input to identify the occurrence ofthe respective patterns identified in the subscription messages, and (2)upon the occurrence of the user input pattern identified in a givensubscription message, notifying the corresponding application via saidsession based protocol and via a signaling channel linking theapplication with the device, wherein each subscription messageoptionally includes a persistence indicator indicating that the deviceis to notify the application for each of multiple occurrences of theuser input pattern identified in the message, and wherein the methodfurther comprises, at the device: (1) determining for each subscriptionmessage whether the persistence indicator is included; (2) if thepersistence indicator is included, then repeating the monitoring andnotifying steps for a subsequent occurrence of the user input pattern;and (3) if the persistence indicator is not included, then ceasing themonitoring for the input pattern upon the first notification of theapplication that the user input pattern has occurred.
 2. A method ofproviding user key press information to a plurality of independent,concurrent applications, comprising: for each of said plurality ofapplications, generating a respective subscription message and providingthe subscription message via a session based protocol to a devicereceiving key presses from a user, the subscription message for eachapplication identifying user input content, the user input contentincluding a respective pattern of user key presses upon whose occurrencethe application is to be notified; and at the device, (1) monitoring thekey presses from the user to identify the occurrence of the respectiveuser key press patterns identified in the subscription messages, and (2)upon the occurrence of the user key press pattern identified in a givensubscription message, notifying the corresponding application via saidsession based protocol and via a signaling channel linking theapplication with the device, wherein the key presses from the user arebuffered within the device, wherein the method further comprises, withinthe device: quarantining key presses occurring after an application hasbeen notified and before receiving a subsequent subscription message,wherein the subsequent subscription message optionally includes a flushindicator indicating that any quarantined digits are to be flushed, andwherein the method further comprises, at the device: (1) determining foreach subscription message whether the flush indicator is included; (2)if the flush indicator is included in a given subscription message, thendisregarding any quarantined digits in determining whether key pressesfrom the user match the pattern specified in the subscription message;and (3) if the flush indicator is not included in the given subscriptionmessage, then including the quarantined digits in determining whetherkey presses from the user match the pattern specified in thesubscription message.
 3. A method of providing user key pressinformation to a plurality of independent, concurrent applications,comprising: for each of said plurality of applications, generating arespective subscription message and providing the subscription messagevia a session based protocol to a device receiving key presses from auser, the subscription message for each application identifying userinput content, the user input content including a respective pattern ofuser key presses upon whose occurrence the application is to benotified; and at the device, (1) monitoring the key presses from theuser to identify the occurrence of the respective user key presspatterns identified in the subscription messages, and (2) upon theoccurrence of the user key press pattern identified in a givensubscription message, notifying the corresponding application via saidsession based protocol and via a signaling channel linking theapplication with the device, wherein the method further comprises, atthe device: upon notifying an application via the respective signalingchannel of the occurrence of the respective pattern of user key presses,suppressing the transmission of the user key presses on a media channelon which media emanating from the user is generally transmitted by thedevice.
 4. A device for receiving input of a predetermined type from auser and providing corresponding user input information to a pluralityof independent, concurrent applications, the device being operative: (1)to receive, from each of said plurality of applications, a respectivesubscription message via a session based protocol, the respectivesubscription message identifying user input content, the user inputcontent including a pattern of user input upon whose occurrence theapplication is to be notified; (2) to monitor the user input to identifythe occurrence of the patterns identified in the subscription messages;and (3) upon the occurrence of the user input pattern identified in agiven subscription message, to notify the corresponding application viasaid session based protocol and via a signaling channel linking theapplication with the device, wherein each subscription messageoptionally includes a persistence indicator indicating that the deviceis to notify the application for each of multiple occurrences of theuser input pattern identified in the message, and wherein the device isfurther operative: (1) to determine for each subscription messagewhether the persistence indicator is included; (2) if the persistenceindicator is included, then to repeat the monitoring and notifying for asubsequent occurrence of the user input pattern; and (3) if thepersistence indicator is not included, then to cease the monitoring forthe input pattern upon the first notification of the application thatthe user input pattern has occurred.
 5. A device for receiving keypresses from a user and providing corresponding user key pressinformation to a plurality of independent, concurrent applications, thedevice being operative: (1) to receive from each of said plurality ofapplications, a subscription message via a session based protocol, thesubscription message identifying user input content, the user inputcontent including a respective pattern of user key presses upon whoseoccurrence the application is to be notified; (2) to monitor the keypresses from the user to identify the occurrence of the respective userkey press patterns identified in the subscription messages; and (3) uponthe occurrence of the user key press pattern identified in a givensubscription message, to notify the corresponding application via saidsession based protocol and via a signaling channel linking theapplication with the device, wherein the device comprises: a bufferoperative to buffer the key presses from the user, wherein the device isfurther operative to quarantine key presses occurring after anapplication has been notified and before receiving a subsequentsubscription message, wherein the subsequent subscription messageoptionally includes a flush indicator indicating that any quarantineddigits are to be flushed, and wherein the device is further operative:(1) to determine for each subscription message whether the flushindicator is included; (2) if the flush indicator is included in a givensubscription message, then to disregard any quarantined digits indetermining whether key presses from the user match the patternspecified in the subscription message; and (3) if the flush indicator isnot included in the given subscription message, then to include thequarantined digits in determining whether key presses from the usermatch the pattern specified in the subscription message.
 6. A device forreceiving key presses from a user and providing corresponding user keypress information to a plurality of independent, concurrentapplications, the device being operative: (1) to receive from each ofsaid plurality of applications, a subscription message via a sessionbased protocol, the subscription message identifying user input content,the user input content including a respective pattern of user keypresses upon whose occurrence the application is to be notified; (2) tomonitor the key presses from the user to identify the occurrence of therespective user key press patterns identified in the subscriptionmessages; (3) upon the occurrence of the user key press patternidentified in a given subscription message, to notify the correspondingapplication via said session based protocol and via a signaling channellinking the application with the device; and (4) upon notifying anapplication via the respective signaling channel of the occurrence ofthe respective pattern of user key presses, to suppress the transmissionof the user key presses on a media channel on which media emanating fromthe user is generally transmitted by the device.